You can bet on the fact that you have earned some respect from him now that you have asserted yourself.
The horse you see in my avatar is Valentino, an OTTB gelding...now 6 years old. When we first took him from the rescue a year and a half ago, he was one of the nastiest animals.....he bit, bucked, reared, charged at you & had no intention of being taught any manners. Getting through to him was such a major accomplishment. I was boarding him with a "friend" who was afraid of him & almost constantly had me bordering re-homing him. I am so relieved I didn't.
Once I got him out of there & home where I had access to him all hours of the day, I finally got the chance to put myself in the role of boss mare.....but that took quite some time. I had to be really tough on him to get his respect.....I mean making him run at a full gallop from one end of the arena to the other & back again several times when he ticked me off. A few times of this and he started to see a pattern emerge.....and after a while he stopped doing the "wrong" thing.
Don't get me wrong.....he still tests me often to see if I am still worthy of the title....but he finds out immediately that I truly am ! I can honestly say that what he have is not a master/slave relationship.....but an communication of what is and is not acceptable. He follows me around like a lovesick puppy dog, and parks that huge 17 hh rump in my face for a scratch.
The other night he was standing in front of our mare's stall and I was standing next to him on the outside....and our 4 month old foal was on the other side of me. I saw him pin his ears back & start to swing his head to lunge at either the mare of the foal, but when he swung toward me & realized he had forgotten I was there, you could see the panic in his eyes & he stopped dead. He knows if I am there at ALL, this kind of behavior will not be tolerated.
It took a long time, and is still in practice, but my dominance over him brought about a respect I really thought I'd never see.
Keep working at letting him know he is NOT in charge. He will come around......